Contacting terminal structure for oxidation products of electrical devices



Feb; 2% 1945. M. LAZARUS 2,370,104

CONTACTING TERMINAL STRUCTURE FOR OXIDATION PRODUCTS OF ELECTRICAL DEVICES Filed Sept. 27, 1943 INVENTOR M5 YfE $424205 BY WM.

ATTORNEY Patented Feb. 20, 1945 CONTACTING TERMINAL STRUCTURE FOR PRODUCTS OF ELECTRICAL Meyer Lazarus, Forest Hills, Long Island, N. Y.

Application September 27, 1943, Serial No. 504,074

Claims. (01. 175-366) My invention relates to improvements in contacting terminal structures for oxidation prod-' ucts of electrical devices such as copper oxide rectifying elements and metal oxide thermo re- In the modification of my invention, which is shown in Fig, 1, ll designates a metal carrier of anelectrical element which may be either a thermo responsive resistance element or a recsponsive elements of the resistance type; and it 5 tifying element, and I! a layer of the oxide of consists in the novel features which are hereinthe metal of the carrier II which is integral after described. therewith.

One of the objects of my invention is to pro- The carrier H may be made of copper and vide a relatively unchanging electrical contact the layer I! of cuprous oxide.

applied to the oxide surface of an oxidized metal Instead of an oxide alone an admixture of carrier of an electrical element, which may be other oxides or chemical compounds with cuprous either a rectifying element or a resistance eleoxide may be used in some cases, if desired.

ment and the like, through an intermediately dis- One such compound may contain cuprous oxide posed coating deposited on the said oxide surand an oxychloride.

face. A contacting soft metal electrode l3, which Another object is to reduce to a minimum the may be preferably a lead plate, is shown as havaging at the junction between the oxide surface ing thereon an electrolytically deposited film of and the contacting electrode or contact element. a nonoxidizable rare metal l5, which metal may A further object is to enable the electrode at be either chromium or bismuth, and is connected said junction to be immune from oxidation by under pressure to the layer 12 on the side of the heat an operating temperatures. latter which is remote from the carrier II, and

Another object of my invention is to reduce a coating M of a substance which isknown in the the electrical resistance at the Junction of the arts as silver graphalloyis shown as placed becontact surfaces of the said devices and thereby tween the layer l2 and the plated surface I! of reduce the contact drop. Y the terminal electrode l3 in contact with the A further object is to have the contacting eleccoating IS. The soft metal of the electrode l3 trode of the terminal structure electrolyticallywith the film l5 thereon conforms itself under plated with a non-oxidizable rare metal, wherepressure to the inequalities of the surface of the by to prevent an increase of resistance at the oxide l2 with the coating l4 thereon, thereby contact of the said electrode with the adjoining producing an intimate contact therebetween and surface of the terminal structure, which surface thereby reducing the electrical contact resistmay be either silver graphalloy, colloidal graphance. ite or a mixture of graphite and silver, if desired. The object of the silver graphalloy is to reduce A still further object is .to establish a low reto a minimum the contact resistance at the juncsistance contact between the oxidized surface of tion of the oxide I2 and the coating I5. the metal carrier and its contacting or adjoining As a result of diligent experimenting I found conductor. silver graphalloy to be superior to any other Other objects and advantages will hereinafter coating on the oxide surface I! and ;to other appear. forms of graphalloy.

I attain these objects by the electrical devices 40 Graphalloy is an imperfect alloy or conjuncand the contacting terminal structures thereof tion of graphite and a soft metal produced by which are illustrated in the accompanying drawfilling the interstices of porous graphite with ing or by any mechanical equivalents or obvious the metal in a state of fusion. modifications of the same. The coating It may first be formed on the said In the drawing Fig. 1 is a cross-section of an 5 layer I2 by rubbing the layer 12' or a part thereof electrical device containing a single element of with a piece of the silver graphalloy which 'may the preferred form of my contacting terminal have a suitable shape. structure. I prefer to cover with the coating l4 only a Fig. 2 is a cross-section of a stack of rectifying portion of the surface of the layer l2 opposite elements such as shown in Fig. 1. the plate l3, to prevent any portion of the layer The thickness of each of the sundry plates M from being brought into contact with the and layers is exaggerated in all the figures of the carrier I I through cracks at the inner and outer drawing. peripheries of the layer l2, whereby to avoid short Similar numerals refer to similar parts circuiting the element "-14. throughout the several views. 66 vThe operation of coating the layer I2 with silver graphalloy may be done either manually or by any suitable machine or contrivance.

Both the layer l2 and the film IS on the plate 13 may be coated with silver graphalloy, if desired.

The film I! of chromium or bismuth on the plate I 3 at the surface of contact thereof under pressure with 'the coating M will maintain a substantially constant minimum contact resistance with the surface of the coating M. This is due to the soft metal l3 causing the chromium of the film l5 to be brought into intimate contact with the coating M.

The chromium or bismuth coated plate i3 is also adapted to withstand relatively high operating temperatures.

As a result 01 diligent experimenting, I found that the coating I5 of chromium or bismuth on the element or electrode 13 is superior to coatings of nickel or tinwhich have been used heretofore.

In the stack of elements which is shown in Fig. 2 the elements are connected and pressed to each other by means of a bolt 22 and nut 23; end pressure plates are shown as placed under the head22a of the bolt 22 and under the nut 23; insulating discs is are shown as placed under the pressure plates 20 to insulate the said plates from the terminals ll and I8 which are shown as having electrical conductors attached thereto. The bolt 22 is shown as insulated by means of a sleeve 2 l.

Variations are possible and parts of my invention may be used without other parts.

I do not, therefore, restrict myself to the details as shown in the drawing.

I claim as my invention and desire to secure by Letters Patent:

1. In a terminal structure for an electrical device a copper carrier, 9. layer of a compound containing the oxide of said carrier on said carrier,

a soft metal electrode cooperating with said layer,

a film of a relatively nonoxidizable rare metal other than gold or platinum on the electrode and a coating of silver graphalloy on said layer firmly adhering thereto interposed between said layer and said-film.

3. In a terminal structure for electrical devices a copper carrier, a layer of a compound containlng cuprous oxide on said carrier, a soft metal electrode cooperating with said layer, a

film of electrolytically deposited chromium on the electrode, and a coating of silver graphalloy on said layer firmlyadhering thereto interposed between said layer and said film.

4. In a terminal structure for electrical devices a copper carrier, a layer of a compound containing cuprous oxide on said carrier, a soft metal electrode cooperating with said layer, a film of bismuth on the electrode and coating of silver graphalloy on said layer firmly adhering thereto interposed between said layer and said film.

5. In a terminal structure for an electrical device a metal carrier,'a layer of a compound containing the oxide of said carrier on said carrier, a soft metal electrode cooperating with said layer, a film of a nonoxidizable rare metal other than gold or platinum on the electrode and a coating of a mixture of graphite and silver on said layer adhering thereto, interposed between said layer and said film.

MEYER LAZARUS. 

